Systems for obtaining write strategy parameters utilizing data-to-clock edge deviations, and related method and optical storage device thereof

ABSTRACT

A system in an optical storage device has a controller which obtains a plurality of write strategy parameters for the optical storage device to write data on an optical storage medium. The write strategy parameters are derived from data-to-clock edge deviations respectively corresponding to a plurality of data set types. Each of the data set types corresponds to a combination of at least a specific target pit length and a specific target land length, or a combination of at least a specific target land length and a specific target pit length.

CROSS REFERENCE TO RELATED APPLICATIONS

This continuation application claims the benefit of co-pending U.S. patent application Ser. No. 10/908,580, filed on May 18, 2005 and incorporated herein by reference.

BACKGROUND

The present invention relates to write strategy tuning of an optical storage device, and more particularly, to systems for obtaining write strategy parameters utilizing data-to-clock edge deviations, and related method and optical storage device thereof.

As multimedia applications continue to progress, the demand for storing massive digital data increases rapidly. As a result, high storage volume and compact size optical storage media such as Compact Discs (CDs) or Digital Versatile Discs (DVDs) are very popular, and optical storage devices such as CD drives or DVD drives have become standard accessories of personal computers, utilized for performing the multimedia applications.

Take the CD drive as an example. When the CD drive is controlled to write data to a CD-Recordable (CD-R) disc, the writing power of a laser diode in the CD drive is usually set to be a specific value, and write pulses corresponding to the data are utilized for recording pits and lands onto the grooves of the CD-R disc. The specific value of the writing power can be derived from an optimal power calibration (OPC) process. On the other hand, through a write strategy tuning process, which is also referred to as a recording strategy tuning process, changing write strategy parameters for controlling widths of the write pulses may increase the accuracy of lengths of pits and lands formed on the CD-R disc. Please refer to related documents of the CD-R specifications (e.g. the Orange Book Part I) for more information.

According to the related art, a specific device such as an oscilloscope can be utilized during the write strategy tuning process. Usually, according to an eye pattern of a plurality of reproduced waveforms shown on the oscilloscope after a trial writing process in advance, a new set of write strategy parameters for controlling the widths of the write pulses are determined, based on experience, by an engineer or researcher. It takes a lot of engineer or researcher's time to utilize this method because the same process must be repeatedly performed for various applicable media and different recording speeds, including at least writing test data, inspecting an eye pattern of reproduced waveforms shown on the oscilloscope, and determining a new set of write strategy parameters by experience according to the eye pattern. The write strategy tuning process mentioned above is time consuming since determining the write strategy parameters by inspecting eye patterns is not an automatic operation. In addition, the write strategy tuning process mentioned above is indefinite since determining a new set of write strategy parameters by experience according to the eye pattern is not quantitative. Under certain situations, an unclear eye pattern would invalidate or interfere with the write strategy tuning process.

A specific instrument such as a time interval analyzer (TIA) or a jitter meter might be helpful for the purpose of deriving information for determining a new set of write strategy parameters. However, similar routine work is also required, and if the TIA or jitter meter is simply coupled for measuring without setting up an additional control system, the same drawbacks caused by the manual tuning process still existed. In addition, the information derived from the specific instrument is usually implicit and therefore takes up a large amount of experienced engineer or researcher's time.

SUMMARY

It is one of the objectives of the claimed invention to provide systems for obtaining write strategy parameters utilizing data-to-clock edge deviations, and related method and optical storage device thereof.

According to a first aspect of the present invention, an exemplary system in an optical storage device is disclosed. The exemplary system includes a controller which obtains a plurality of write strategy parameters for the optical storage device to write data on an optical storage medium. The write strategy parameters are derived from data-to-clock edge deviations respectively corresponding to a plurality of data set types. Each of the data set types corresponds to a combination of at least a specific target pit length and a specific target land length, or a combination of at least a specific target land length and a specific target pit length.

According to a second aspect of the present invention, an exemplary system in an optical storage device is disclosed. The exemplary system includes a detector, a calculation module, and a controller. The detector is capable of configuring to detect a plurality of lengths, each length corresponding to a pit or a land on an optical storage medium accessed by the optical storage device. The calculation module is capable of configuring to perform calculations corresponding to a plurality of data set types and generate a plurality of data-to-clock edge deviations respectively corresponding to the data set types, wherein each of the data set types corresponds to a combination of at least a specific target pit length and a specific target land length, or a combination of at least a specific target land length and a specific target pit length. The controller is capable of configuring to calibrate a plurality of write strategy parameters respectively corresponding to the data set types utilizing the data-to-clock edge deviations, wherein the write strategy parameters are utilized to write data on the optical storage medium.

According to a third aspect of the present invention, an exemplary method for obtaining write strategy parameters for an optical storage device is disclosed. The exemplary method includes the following steps: writing data on optical storage medium; reading data written on the optical storage medium to generate a reproduced signal; detecting a plurality of lengths from the reproduced signal, each length corresponding to a pit or a land on the optical storage medium; performing calculations corresponding to a plurality of data set types and generating a plurality of data-to-clock edge deviations respectively corresponding to the data set types, wherein each of the data set types corresponds to a combination of at least a specific target pit length and a specific target land length, or a combination of at least a specific target land length and a specific target pit length; and obtaining the write strategy parameters respectively corresponding to the data set types utilizing the data-to-clock edge deviations.

According to a fourth aspect of the present invention, an exemplary optical storage device which writes data on an optical storage medium utilizing a plurality of write strategy parameters obtained by the above-mentioned exemplary method is disclosed.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system for tuning write strategy parameters of an optical storage device according to one embodiment of the present invention.

FIG. 2 is a length compensation illustration utilizing data-to-clock edge deviations according to one embodiment of the present invention.

FIG. 3 is a flowchart of a method for tuning write strategy parameters according to one embodiment of the present invention.

FIG. 4 is a table illustrating data set types corresponding to target length combinations according to one embodiment of the present invention.

FIG. 5 is a block diagram of a system for tuning write strategy parameters of an optical storage device according to one embodiment of the present invention.

FIG. 6 is a block diagram of a system for tuning write strategy parameters of an optical storage device according to one embodiment of the present invention.

FIG. 7 illustrates sample points on a reproduced signal with respect to an EFM data clock, where a difference between a specific sample point's value and a predetermined value is utilized for representing a data-to-clock edge deviation according to one embodiment of the present invention.

FIG. 8 illustrates a variation of the embodiment shown in FIG. 6.

DETAILED DESCRIPTION

The present invention provides systems for tuning a plurality of write strategy parameters of an optical storage device. According to a first aspect, one of the systems is a circuit for tuning the write strategy parameters, where the circuit is positioned in the optical storage device. According to a second aspect, one of the systems is substantially the optical storage device itself. For simplicity, the first aspect is utilized in the following description. However, the second aspect is also applicable to the detailed embodiments.

FIG. 1 illustrates a block diagram of a system 100C for tuning a plurality of write strategy parameters of an optical storage device 100 according to a first embodiment, where the system 100C is a circuit positioned in the optical storage device 100 accessing an optical storage medium 102. Please note that for simplicity, this embodiment is described utilizing a CD-R disc as the optical storage medium 102 and utilizing a CD drive as the optical storage device 100. Those skilled in the art should understand that other kinds of optical storage media such as a DVD-R disc, a DVD+R disc, or a DVD-RAM disc, and corresponding optical storage devices such as a DVD drive are applicable according to other embodiments of the present invention.

As shown in FIG. 1, an optical pickup 110 of the optical storage device 100 reads data from the optical storage medium 102 to generate a raw radio frequency (RF) signal 111 in a reading mode of the optical storage device 100. A waveform equalizer 112 of the optical storage device 100 equalizes the raw RF signal 111 to generate a reproduced signal, which is the RF signal 113 in the first embodiment. In addition, a slicer 114 of the optical storage device 100 slices the RF signal 113 to generate a sliced signal 115. Operation principles of the optical pickup 110, the waveform equalizer 112, and the slicer 114 are well known in the art and therefore not described in detail here.

Within the optical storage device 100 shown in FIG. 1, a modulator 160, a write pulse generator 162, and a radiation source driver 164 co-operate to drive the optical pickup 110 according to the write strategy parameters, which is tuned by the system 100C through a control signal 151 according to the sliced signal 115. The modulator 160 is coupled to an encoder (not shown) of the optical storage device 100 for modulating encoded data outputted by the encoder to generate a modulated signal 161 carrying eight-to-fourteen modulation (EFM) information. The write pulse generator 162 generates write pulses corresponding to the EFM information carried by the modulated signal 161 according to the write strategy parameters mentioned above, and outputs the write pulses carried by a write pulse signal 163. In addition, the radiation source driver 164 generates a driving signal 165 according to the write pulse signal 163 to drive the optical pickup 110. Operation principles of the modulator 160, the write pulse generator 162, and the radiation source driver 164 are well known in the art and therefore not described in detail here.

According to this embodiment, the system 100C comprises a phase-locked loop (PLL) 120, a detector such as an EFM length detector 130 shown in FIG. 1, a calculation module 140, and a controller such as a write pulse controller 150 shown in FIG. 1, where the calculation module 140 comprises a pattern dependency classifier 142 and a data-to-clock edge deviation calculator 144. The PLL 120 generates an EFM data clock CLK according to the sliced signal 115 by locking the channel bit rate (1/T) of the sliced signal 115, where the period of the EFM data clock CLK is considered to be 1 T. The EFM length detector 130 derives EFM information carried by the sliced signal 115 according to the EFM data clock CLK, and detects a plurality of lengths, where each length corresponds to a pit or a land recorded on the optical storage medium 102. The sliced signal 115 is typically a square wave having various intervals between rising edges and falling edges thereof and various intervals between falling edges and rising edges thereof. In this embodiment, the EFM length detector 130 measures intervals between rising edges and falling edges of the sliced signal 115 and/or intervals between falling edges and rising edges of the sliced signal 115 as the lengths mentioned above, where each interval corresponds to a pit or a land. As a result, the lengths comprise pit lengths P corresponding to pits, and land lengths L corresponding to lands. Each of the pit lengths P represents a pit recorded along a groove on the optical storage medium 102, and each of the land lengths L represents a land along the groove. Please note that the sliced signal 115 of another embodiment of the present invention may carry EFM plus (EFM+) information (e.g. for an embodiment of DVD-R) or other information complying with a variation of the EFM/EFM+ specification.

In the first embodiment, the pit lengths and the land lengths derived from the sliced signal 115 are multiples of clock period T and ranging from 3 T to 11 T in an ideal case of the CD-R disc. That is, a length P of a pit or a length L of a land can be 3 T, 4 T, . . . , or 11 T. So it is reasonable that a reference signal for measuring the lengths of the pits and the lands (e.g. the EFM data clock CLK) has a period less than or equal to T. According to this embodiment, the reference signal inputted into the EFM length detector 130 is the EFM data clock CLK, so the period of the reference clock is T. In a real case of the CD-R disc, the lengths L and P carried by the output signal 131 of the EFM length detector 130 are usually not exact multiples of T. The calculation module 140 may perform calculations corresponding to a plurality of data set types and generate a plurality of data-to-clock edge deviations respectively corresponding to the data set types, where the data-to-clock edge deviations are carried by an output signal 145 of the data-to-clock edge deviation calculator 144. Each of the data set types corresponds to a combination of at least a specific target pit length (e.g. 3 T, 4 T, . . . , 11 T) and a specific target land length (e.g. 3 T, 4 T, . . . , 11 T) or a combination of at least a specific target land length and a specific target pit length.

The pattern dependency classifier 142 classifies a plurality of data sets into the data set types. In this embodiment, each data set, being (P, L) or (L, P), comprises two lengths, where a data set (P, L) means one length corresponds to a pit and another corresponds to an adjacent land, and a data set (L, P) means one length corresponds to a land and another corresponds to an adjacent pit. Here, notation such as (P_(nT), L_(mT)) or (L_(nT), P_(mT)) is utilized for denoting the data set types mentioned above, where nT or mT indicates the length in terms of the clock period T, n=3, 4, . . . , 11 and m=3, 4, . . . , 11 in this embodiment. Each of the data set types (L_(nT), P_(mT)), e.g. a data set type (L_(n0*T), P_(m0*T)) having n=n0 and m=m0, is utilized for classifying data sets (L, P) corresponding to a land having a target land length of n0*T followed by an adjacent pit having a target pit length of m0*T. Similarly, each of the data set types (P_(nT), L_(mT)), e.g. a data set type (P_(n0*T), L_(m0*T)) having n=n0 and m=m0, is utilized for classifying data sets (P, L) corresponding to a pit having a target pit length of n0*T followed by an adjacent land having a target land length of m0*T. It is noted that each of the data set types (L_(nT), P_(mT)), e.g. the data set type (L_(n0*T), P_(m0*T)), corresponds to a combination (n0*T, m0*T) of a specific target land length n0*T and a specific target pit length m0*T, and each of the data set types (P_(nT), L_(mT)), e.g. the data set type (P_(n0*T), L_(m0*T)), corresponds to a combination (n0*T, m0*T) of a specific target pit length n0*T and a specific target land length m0*T. There are 9 possible values for n and m, so there are 9*9 combinations for each of the data set types (L_(nT), P_(mT)) and (P_(nT), L_(mT)), and the total number of data set types would be 9*9*2=162.

In addition, the pattern dependency classifier 142 may classify the data sets (L, P) as data set type (L_(n0*T), P_(m0*T)) if the lengths L and P satisfy:

(n0−0.5)*T≦L≦(n0+0.5)*T and (m0−0.5)*T≦P≦(m0+0.5)*T.

Similarly, the pattern dependency classifier 142 may classify the data sets (P, L) as data set type (P_(n0*T), L_(m0*T)) if the lengths P and L satisfy:

(n0−0.5)*T≦P≦(n0+0.5)*T and (m0−0.5)*T≦L≦(m0+0.5)*T.

The data-to-clock edge deviation calculator 144 may calculate the data-to-clock edge deviations respectively corresponding to the data set types (L_(nT), P_(mT)) and (P_(nT), L_(mT)) as follows. The data-to-clock edge deviation calculator 144 calculates a plurality of data-to-clock edge lengths, where each data-to-clock edge length is an interval between a rising/falling edge of the reference clock mentioned above (i.e. the EFM data clock CLK in this embodiment) and a transition edge of the sliced signal 115. Additionally, the data-to-clock edge deviation calculator 144 calculates a plurality of differences to generate the data-to-clock edge deviations respectively corresponding to the data set types (L_(nT), P_(mT)) and (P_(nT), L_(mT)). Each of the differences mentioned above is a difference between a data-to-clock edge length and a target data-to-clock edge length that is a predetermined value corresponding to a specific data set type (L_(n0*T), P_(m0*T)) or (P_(n0*T), L_(m0*T)).

Take the situation shown in FIG. 2 as an example. FIG. 2 is a length compensation illustration utilizing the data-to-clock edge deviations according to the first embodiment, where two pits A and B both corresponding to a target length P_(4T) (i.e. the target length of 4 T-pit) and a land corresponding to a target length L_(5T) (i.e. the target length of 5 T-land) are illustrated. As shown in FIG. 2, Ttopr and Tlast respectively denote write strategy parameters for controlling the beginning location and the end location of pits. According to this embodiment, the write strategy parameters Ttopr(n, m) represent the write strategy parameters for controlling the beginning location of the pits corresponding to the data set types (L_(nT), P_(mT)), and the write strategy parameters Tlast(n, m) represent the write strategy parameters for controlling the end location of the pits corresponding to the data set types (P_(nT), L_(mT)). Here, pit A and the adjacent land following thereof (i.e. the 5 T-land between pits A and B) correspond to a data set type (P_(4T), L_(5T)), and this 5 T-land and pit B correspond to a data set type (L_(5T), P_(4T)). In addition, the write strategy parameter Tlast corresponding to the end location of pit A is referred to as Tlast(4, 5), and the write strategy parameter Ttopr corresponding to the beginning location of pit B is referred to as Ttopr(5, 4).

The data-to-clock edge deviation calculator 144 calculates a data-to-clock edge length d1. In this embodiments, the data-to-clock edge length d1 is an interval between time point D of a falling edge of the sliced signal 115, i.e. the time point corresponding to the end location of pit A, and a subsequent rising edge of the EFM data clock CLK, e.g. time point d. Please note that time point D is substantially the same time point as when the value of the RF signal 113 crosses the predetermined value such as the value corresponding to the slicing level of the slicer 114. The data-to-clock edge deviation calculator 144 detects time point D by detecting the transition of the sliced signal 115 from high to low. Same method can be applied to calculate each of the data-to-clock edge lengths corresponding to data set type (P_(4T), L_(5T)). Additionally, the data-to-clock edge deviation calculator 144 calculates a plurality of differences to generate data-to-clock edge deviations corresponding to the data set types. In some embodiments, the data-to-clock edge deviation calculator 144 generates the data-to-clock edge deviation of a particular data set type by conducting statistics analysis on the differences corresponding to the data set type. The statistics analysis may be averaging the difference, or finding the most frequent value of the differences. Each of the differences mentioned above is a difference between a data-to-clock edge length and a target data-to-clock edge length, for example, 0.5 T in this embodiment. The target data-to-clock edge length corresponding to data set types (P_(4T), L_(5T)) is 0.5 T because the time point corresponding to the end location of pit A in an ideal case is supposed to be time point Do.

Similarly, the data-to-clock edge deviation calculator 144 calculates a data-to-clock edge length d2, which is an interval between time point E of a rising edge of the sliced signal 115, i.e. the time point corresponding to the beginning location of pit B and a subsequent rising edge of the EFM data clock CLK, e.g. time point e. Please note that time point E is substantially the same time point as when the value of the RF signal 113 crosses the predetermined value such as the value corresponding to the slicing level of the slicer 114. The data-to-clock edge deviation calculator 144 detects time point E by detecting transition of the sliced signal 115 from low to high. Same method can be applied to calculate the data-to-clock edge lengths corresponding to data set type (L_(5T), P_(4T)). Additionally, the data-to-clock edge deviation calculator 144 calculates a plurality of differences to generate data-to-clock edge deviations corresponding to the data set types, where each of the differences mentioned above is a difference between a data-to-clock edge length and a target data-to-clock edge length. In this embodiment, the target data-to-clock edge length corresponding to data set type (L_(5T), P_(4T)) is determined to be 0.5 T because the time point corresponding to the beginning location of pit B in an ideal case is supposed to be time point Eo.

It is noted that the classification information generated by the pattern dependency classifier 142 can be sent to the write pulse controller 150 through the data-to-clock edge deviation calculator 144 if needed since the transmission from the data-to-clock edge deviation calculator 144 to the write pulse controller 150 is digital. Similarly, the detection result(s) generated by the EFM length detector 130 can be sent to the data-to-clock edge deviation calculator 144 through the pattern dependency classifier 142 if needed since the transmission from the pattern dependency classifier 142 to the data-to-clock edge deviation calculator 144 is digital. In a variation of the first embodiment, the write pulse controller 150 can be coupled to the pattern dependency classifier 142 through direct connection, and the data-to-clock edge deviation calculator 144 can also be coupled to the EFM length detector 130 through direct connection.

In a variation of the first embodiment, the target data-to-clock edge length utilized for calculating the differences to generate the data-to-clock edge deviations corresponding to a specific data set type (L_(n0*T), P_(m0*T)) can be an average of a plurality of data-to-clock edge lengths corresponding to the specific data set type (L_(n0*T), P_(m0*T)). Similarly, the target data-to-clock edge length utilized for calculating the differences to generate the data-to-clock edge deviations corresponding to a specific data set type (P_(n0*T), L_(m0*T)) can be an average of a plurality of data-to-clock edge lengths corresponding to the specific data set type (P_(n0*T), L_(m0*T)). In another variation of the first embodiment, the target data-to-clock edge length utilized for calculating the differences to generate the data-to-clock edge deviations corresponding to a specific data set type (L_(n0*T), P_(m0*T)) or (P_(n0*T), L_(m0*T)) can be an average of a plurality of data-to-clock edge lengths corresponding to the specific data set type (L_(n0*T), P_(m0*T)) and a plurality of data-to-clock edge lengths corresponding to the specific data set type (P_(n0*T), L_(m0*T)).

It is noted that the write strategy parameters such as Ttopr(n, m) and Tlast(n, m) can be tuned automatically since specific devices (e.g. the oscilloscope mentioned above) are no longer required according to the present invention. In addition, without the agency of external devices, the write pulse controller 150 may tune the write strategy parameters according to the data-to-clock edge deviations generated by the calculation module 140, so the write strategy parameters can be tuned automatically on system or on chip according to the present invention. Through tuning the write strategy parameters according to the data-to-clock edge deviations, pit lengths or land lengths corresponding to data newly written on the optical storage medium 102 utilizing the latest updated write strategy parameters may approach target multiples of T.

FIG. 3 illustrates a flowchart of a method 910 for tuning write strategy parameters of an optical storage device according to one embodiment of the present invention. The method 910 may be implemented by system 100C shown in FIG. 1.

In Step 912, under the control of a firmware code executed by a micro-processing unit (MPU) of the optical storage device 100, the optical storage device 100 writes data on the optical storage medium 102 utilizing initial values of the write strategy parameters corresponding to a specific rotational speed of the optical storage device 100.

In Step 914, the optical storage device 100 reads the data newly written on the optical storage medium 102 to generate the sliced signal 115.

In Step 916, the EFM length detector 130 of the system 100C detects lengths P of pits and lengths L of lands by measuring the sliced signal 115.

In Step 918, the calculation module 140 calculates data-to-clock edge deviations corresponding to data set types (L_(nT), P_(mT)) and (P_(nT), L_(mT)), where n=3, 4, . . . , 11 and m=3, 4, . . . , 11 in this embodiment.

In Step 920, the MPU executing the firmware code determines if tuning of the write strategy parameters is needed. If any of the data-to-clock edge deviations is greater than a specific threshold, the MPU executing the firmware code determines that tuning of the write strategy parameters is needed, so Step 922 will be executed; otherwise, enter Step 910E. The MPU may determine to enter Step 922 directly without examining Step 920 if initial values of the write strategy parameters are certain to be imperfect. In addition, although the write strategy parameters described in Steps 920 and 922 are plural write strategy parameters for simplicity as shown in FIG. 3, this is not a limitation of the present invention. Both Steps 920 and 922 can be described utilizing a singular form of “write strategy parameter” if tuning of only a single write strategy parameter is needed. Repeated explanation of the singular or plural form for similar situations is therefore unnecessary in the following.

If the MPU executing the firmware code determines to enter Step 922, the system 100C tunes the write strategy parameters utilizing the data-to-clock edge deviations as mentioned.

In Step 924, under the control of the MPU executing the firmware code, the optical storage device 100 writes data on the optical storage medium 102 utilizing the latest values of the write strategy parameters.

Various data set types corresponding to combinations of a target land length and a target pit length for this embodiment are illustrated in the table shown in FIG. 4. The meaning of the combinations has been explained as mentioned and is not repeated here.

Please note that the number of data set types (L_(nT), P_(mT)) and (P_(nT), L_(mT)) according to another embodiment implemented for DVD-R disc or DVD+R disc mentioned above can be derived as follows:

10*10*2=200;

since n=3, 4, . . . , 11, 14 and m=3, 4, . . . , 11, 14 for the DVD-R disc or the DVD+R disc.

FIG. 5 is a block diagram of a system 200C for tuning write strategy parameters of an optical storage device 200 according to a second embodiment of the present invention. The second embodiment is similar to the first embodiment, where the differences are described as follows. The reference signal inputted into the EFM length detector 130 is a reference clock CLK2 generated by an oscillator 220. It is not necessary for the frequency of the reference clock CLK2 to be equal to the frequency of the EFM data clock CLK.

FIG. 6 is a block diagram of a system 300C for tuning write strategy parameters of an optical storage device 300 according to a third embodiment of the present invention. The third embodiment is similar to the first embodiment, where the differences are described as follows. The system 300C comprises a sampling circuit coupled to the waveform equalizer 112 to receive the reproduced signal such as the RF signal 113. The sampling circuit is utilized for sampling the reproduced signal to generate a digital signal, which is a digital RF signal 315 in this embodiment. As shown in FIG. 6, the sampling circuit comprises an analog-to-digital converter (ADC) 314 and a PLL 320. The ADC 314 performs analog-to-digital conversion on the RF signal 113 according to a reference clock CLK3 to generate the digital RF signal 315, and the PLL 320 generates the reference clock CLK3 according to the digital RF signal 315.

The system 300C further comprises an EFM length detector 330, a calculation module 340, and a write pulse controller 350, where the calculation module 340 comprises a pattern dependency classifier 342 and a data-to-clock edge deviation calculator 344. The signal utilized for detecting the lengths is the digital RF signal 315, not the sliced signal 115. The EFM length detector 330 detects intervals between time points by observing the value of the digital RF signal 315, and generates the lengths of the intervals, where each interval corresponds to a pit or a land. The boundary of the intervals can be determined by a predetermined value, for example, a middle value between a maximum value and a minimum value carried by the digital RF signal 315, e.g. an average of the maximum and minimum values. Such a middle value plays a role like the slicing level mentioned in the previous embodiments.

FIG. 7 illustrates sample points (which are drawn with “s”) on a reproduced signal such as the RF signal 113, where a difference d3 between a specific sample point's value and a predetermined value (for example, the middle value mentioned above) can be an indication for a data-to-clock edge deviation d4. According to the waveform of the RF signal shown in FIG. 7, most of the sample points crossing the predetermined value are perfectly aligned to falling edges of the EFM data clock, so the values of most data-to-clock edge deviations are zero. The specific sample point's value mentioned above means a value sampled at the specific sampling time and carried by the digital RF signal 315. Differences between sample points' value and the predetermined value (for example, the difference d3) can represent data-to-clock edge deviations (for example, the data-to-clock edge deviation d4), and the lengths and the data-to-clock edge deviations can be derived accordingly. Therefore, the calculation module 340 may derive the data-to-clock edge deviations by calculating differences between a predetermined value (for example, the middle value) and the value of the digital RF signal 315 around the time points when the value of the digital RF signal 315 crosses the predetermined value.

Here, the pattern dependency classifier 342 performs the same function as the pattern dependency classifier 142 while the EFM length detector 330 may output lengths L and P carried by the output signal 331 similar to the output signal 131. The data-to-clock edge deviation calculator 344 of this embodiment calculates the data-to-clock edge deviations utilizing the approached direct line mentioned above. In addition, the write pulse controller 350 performs the same function as the write pulse controller 150 while the calculation module 340 may output the data-to-clock edge deviations carried by the output signal 345 similar to the output signal 145.

FIG. 8 illustrates a variation of the embodiment shown in FIG. 6, where an interpolator 416 coupled between the ADC 314 and the PLL 320 is utilized. The PLL 320 generates a reference clock CLK4 according to an interpolated signal 417 generated by the interpolator 416, and the interpolator 416 performs an interpolation operation according to the digital RF signal 315 and the reference clock CLK4. In this variation, the input of the EFM length detector 330 is replaced with the interpolated signal 417. Operation principles of the interpolator 416 are well known in the art and therefore not described in detail here.

In addition, although in the embodiments mentioned above, each of the data set types corresponds to a combination of two target lengths, such as (P, L) or (L, P), this is not a limitation of the present invention. In other embodiments of the present invention, each or one of the data set types may correspond to a combination of at least a specific target pit length and specific target land lengths, or a combination of at least a specific target land length and specific target pit lengths, or a combination of specific target land lengths and specific target pit lengths. For example, each of the data set types may contain a combination of three lengths, such as (P₁, L, P₂), (L₁, P, L₂). As a result, the write strategy parameters can be tuned further according to more adjacent pits or lands.

It should be noted that the present invention could be implemented by means of hardware including a plurality of distinct elements, or by means of a suitably programmed computer. In the system claims detailing a plurality of means, several means can be embodied by the same hardware or software device.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

1. A system in an optical storage device, comprising: a controller, obtaining a plurality of write strategy parameters for the optical storage device to write data on an optical storage medium, wherein the write strategy parameters are derived from data-to-clock edge deviations respectively corresponding to a plurality of data set types, and each of the data set types corresponds to a combination of at least a specific target pit length and a specific target land length, or a combination of at least a specific target land length and a specific target pit length.
 2. The system of claim 1, further comprising: a detector for detecting a plurality of lengths according to a reproduced signal generated by the optical storage device accessing the optical storage medium, and each length corresponding to a pit or a land.
 3. The system of claim 2, further comprising: a slicer for slicing the reproduced signal to generate a sliced signal; wherein the detector detects intervals between rising edges and falling edges of the sliced signal and/or intervals between falling edges and rising edges of the sliced signal as the lengths, and each interval corresponds to a pit or a land.
 4. The system of claim 3, further comprising: a calculation module for calculating a plurality of data-to-clock edge lengths and a plurality of differences to generate the data-to-clock edge deviations respectively corresponding to the data set types, wherein each data-to-clock edge length is an interval between a rising or falling edge of a first reference clock and a rising or falling edge of the sliced signal, and each difference is a difference between a data-to-clock edge length and a target data-to-clock edge length, wherein the target data-to-clock edge length is a predetermined value corresponds to a specific data set type or an average of a plurality of data-to-clock edge lengths corresponding to a specific data set type.
 5. The system of claim 4, further comprising: a phase-locked loop (PLL) for generating the first reference clock according to the sliced signal; wherein the detector and the calculation module are coupled to the PLL, and the detector detects the lengths according to the first reference clock.
 6. The system of claim 4, further comprising: a phase-locked loop (PLL) for generating the first reference clock according to the sliced signal; and an oscillator for generating a second reference clock; wherein the detector is coupled to the oscillator and detects the lengths according to the second reference clock, and the calculation module is coupled to the PLL.
 7. The system of claim 2, further comprising: a sampling circuit for sampling the reproduced signal to generate a digital signal; wherein the detector is coupled to the sampling circuit and detects intervals between time points when the value of the digital signal crosses a predetermined value to generate the lengths, and each interval corresponds to a pit or a land.
 8. The system of claim 7, wherein the sampling circuit further comprises: an analog-to-digital converter (ADC) for performing analog-to-digital conversion on the reproduced signal according to a reference clock to generate the digital signal; and a phase-locked loop (PLL) coupled to the ADC for generating the reference clock according to the digital signal.
 9. The system of claim 7, wherein the sampling circuit further comprises: an analog-to-digital converter (ADC) for performing analog-to-digital conversion on the reproduced signal; an interpolator coupled to the ADC for performing an interpolation operation according to a reference clock and results generated by the ADC to generate the digital signal; and a phase-locked loop (PLL) coupled to the interpolator for generating the reference clock according to the digital signal.
 10. The system of claim 1, further comprising: a calculation module, comprising: a pattern dependency classifier for classifying a plurality of data sets into the data set types, each data set comprising lengths corresponding to a pit and an adjacent land or lengths corresponding to a land and an adjacent pit, respectively; and a data-to-clock edge deviation calculator coupled to the pattern dependency classifier for calculating the data-to-clock edge deviations respectively corresponding to the data set types.
 11. A system in an optical storage device, comprising: a detector, capable of configuring to detect a plurality of lengths, each length corresponding to a pit or a land on an optical storage medium accessed by the optical storage device; a calculation module, capable of configuring to perform calculations corresponding to a plurality of data set types and generate a plurality of data-to-clock edge deviations respectively corresponding to the data set types, wherein each of the data set types corresponds to a combination of at least a specific target pit length and a specific target land length, or a combination of at least a specific target land length and a specific target pit length; and a controller, capable of configuring to calibrate a plurality of write strategy parameters respectively corresponding to the data set types utilizing the data-to-clock edge deviations, wherein the write strategy parameters are utilized to write data on the optical storage medium.
 12. A method for obtaining write strategy parameters for an optical storage device, comprising: writing data on optical storage medium; reading data written on the optical storage medium to generate a reproduced signal; detecting a plurality of lengths from the reproduced signal, each length corresponding to a pit or a land on the optical storage medium; performing calculations corresponding to a plurality of data set types and generating a plurality of data-to-clock edge deviations respectively corresponding to the data set types, wherein each of the data set types corresponds to a combination of at least a specific target pit length and a specific target land length, or a combination of at least a specific target land length and a specific target pit length; and obtaining the write strategy parameters respectively corresponding to the data set types utilizing the data-to-clock edge deviations.
 13. The method of claim 12, wherein the step of detecting the lengths further comprises: slicing the reproduced signal to generate a sliced signal; and detecting intervals between rising edges and falling edges of the sliced signal and/or intervals between falling edges and rising edges of the sliced signal as the lengths, wherein each interval corresponds to a pit or a land.
 14. The method of claim 13, wherein the step of performing calculations corresponding to the data set types and generating the data-to-clock edge deviations respectively corresponding to the data set types further comprises: calculating a plurality of data-to-clock edge lengths, each data-to-clock edge length being an interval between a rising or falling edge of a first reference clock and a rising or falling edge of the sliced signal; and calculating a plurality of differences to generate the data-to-clock edge deviations respectively corresponding to the data set types, each difference being a difference between a data-to-clock edge length and a target data-to-clock edge length, wherein the target data-to-clock edge length is a predetermined value corresponding to a specific data set type or an average of a plurality of data-to-clock edge lengths corresponding to a specific data set type.
 15. The method of claim 14, further comprising: generating the first reference clock according to the sliced signal.
 16. The method of claim 15, wherein the step of generating the first reference clock according to the sliced signal further comprises generating the first reference clock utilizing a phase-locked loop (PLL), and the step of detecting the lengths further comprises: detecting the lengths according to the first reference clock.
 17. The method of claim 15, wherein the step of generating the first reference clock according to the sliced signal further comprises generating the first reference clock utilizing a phase-locked loop (PLL), and the step of detecting the lengths further comprises: generating a second reference clock utilizing an oscillator; and detecting the lengths according to the second reference clock.
 18. The method of claim 12, wherein the step of detecting the lengths further comprises: sampling the reproduced signal to generate a digital signal; and detecting intervals between time points when the value of the digital signal crosses a predetermined value to generate the lengths, wherein each interval corresponds to a pit or a land.
 19. The method of claim 18, wherein the step of performing calculations corresponding to the data set types and generating the data-to-clock edge deviations respectively corresponding to the data set types further comprises: calculating differences between the value of the digital signal and the predetermined value around the time points when the value of the digital signal crosses the predetermined value to generate the data-to-clock edge deviations.
 20. The method of claim 18, wherein the step of sampling the reproduced signal further comprises: performing analog-to-digital conversion on the reproduced signal according to a reference clock to generate the digital signal; and generating the reference clock according to the digital signal utilizing a phase-locked loop (PLL).
 21. The method of claim 12, wherein the step of performing calculations corresponding to the data set types and generating the data-to-clock edge deviations respectively corresponding to the data set types further comprises: classifying a plurality of data sets into the data set types, each data set comprising lengths corresponding to a pit and an adjacent land or lengths corresponding to a land and an adjacent pit, respectively; and calculating the data-to-clock edge deviations respectively corresponding to the data set types.
 22. The method of claim 12, wherein in the step of performing calculations corresponding to the data set types and generating the data-to-clock edge deviations respectively corresponding to the data set types, each of the data set types corresponds to a combination of at least a specific target pit length and specific target land lengths, or a combination of at least a specific target land length and specific target pit lengths, or a combination of specific target land lengths and specific target pit lengths.
 23. An optical storage device, writing data on an optical storage medium utilizing a plurality of write strategy parameters obtained by the method claimed in claim
 12. 